Microelectromechanical system (MEMS) devices have been recently utilized in order to obtain devices with variable physical properties. Examples of these MEMS devices include devices with variable physical properties, such as digital micromirror devices (DMDs), and devices with variable electrical properties, such as variable capacitors or variable inductors. Generally, each of these MEMS devices comprises a moveable piece whose movement, when actuated by, e.g., an electrode, causes a change in the variable property of the device.
Generally, well-known semiconductor manufacturing techniques have been utilized to great effect in forming these moveable pieces within the MEMS devices. Using these techniques, parts which are intended to be moveable are initially manufactured as an immovable layer over a sacrificial layer such as a photoresist. Following the completion of the manufacturing of the moveable piece, the sacrificial layer is then removed, thereby freeing the moveable piece to move.
However, when using these processes the topography of the standard photoresist typically used as a sacrificial layer is limited by the fluid dynamic characteristics of the photoresist from forming a flat surface over the underlying features. Such a non-planar surface can create problems during further processing of the device.
Additionally, the use of a typical photoresist also typically uses a high temperature dry strip in order to remove the sacrificial layer. Not only may this result in a larger thermal budget for the overall process, but such a high temperature process also may affect the physical characteristics of the MEMS structure itself, creating defects within the MEMS structure. These defects can reduce the efficiency of the MEMS device itself, and may cause a complete failure of the structure in general.